Ever tried to take a macro shot of a flower and find that part of the image is out of focus? The solution can be a focus stack. Photoshop can assemble an entire stack of photos into one image that gives a much improved focus over any one image. The actual Photoshop program is a must for this one.
To take the image, you have to set your camera on manual focus and mount the camera to a stable tripod. Then take a series of images without moving the camera (a cable release will help) but between each image manually change the focus just a bit. Continue until you get all parts of interest in focus in at least one frame.
Then download to your computer, open Photoshop and go to File >Scripts>Load files into Stack. Browse for the relevant files and load them making sure to check the box for auto alignment. Once loaded you will have a layer for each image you selected. Then highlight (select) all layers. Select the first layer, hold down the shift key and select the last layer. All layers will be selected. Then go to Edit > Auto Blend Layers and select Stack Images and be sure to check the box for Seamless Tones and Colors. The rest is automated. It will make layer masks and combine the image automatically into a focused image.
The image above is created from a stack of 11 images. It is particularly hard to get the throat of a flower in focus as well as the petals without this technique since depth of field is not sufficient in macro photography applications. The photo stack is the solution. Below is a shot of a Datura bloom, normally hard to get with a macro shot since it has a deep throat on the trumpet shaped flower. The photo stack renders great detail.